The present invention relates to a distance measuring apparatus for radiating a light beam to an object to be measured and measuring a distance to the object on the basis of the light reflected by the object.
Jpn. Pat. Appln. KOKAI Publication No. 7-253460 discloses a distance measuring apparatus having a prism for splitting light radiated from a transmission lens into a plurality of directions in order to detect obstacles in a plurality of directions. Jpn. Pat. Appln. KOKAI Publication No. 6-118161 discloses an optical sensing apparatus for deforming a light transmission pattern by arranging diffraction gratings in front of a semiconductor laser.
Both of the above prior art publications teach a technique for expanding the detection range by expanding the radiation angle of a light beam. However, they do not teach a technique for maintaining the intensity of a reflection signal in the expanded radiation angle.